CAR-engineered microglia harness phagocytosis to target brain tumor in organoid models

Glioblastoma (GBM) is among the most aggressive and lethal brain tumors, and standard treatment offers only modest survival benefits. Chimeric antigen receptor (CAR) T cell therapy has transformed the treatment of hematologic cancers, but its efficacy in GBM remains limited. Here we develop a CAR-engineered microglia (CAR-MG) platform and an organoid-based framework to test whether programmable microglial phagocytosis can be directed against GBM. We isolate microglia (MG) from human cortical organoids and engineer them to express a CAR targeting EGFRvIII, a recurrent tumor-specific EGFR deletion variant in GBM. In a 2D co-culture, CAR-MG selectively eliminates GBM cells through phagocytosis. In a 3D GBM-cortical organoid model, CAR-MG infiltrates tumor sites and depletes GBM cells over extended culture. Single-cell RNA sequencing (scRNA-seq) shows elevated phagocytic pathways in CAR-MG and detects internalized tumor-derived transcripts, which resolve phagocytosis-resistance programs. These results support CAR-MG as a myeloid CAR modality for human brain organoid models.